Both the FSS and DSS are functions related to scanning a system and obtaining details about it. It seems odd that the FSS is its own full screen mode, while the DSS is a firegroup from the main cockpit, until deployed, at which point it becomes its own full screen mode.
My suggestion would be to merge the FSS and DSS, accessing the DSS via the FSS screen. So, when nearing a planet, switch to FSS, and then call access the DSS functionality from there.
My suggestion would be to merge the FSS and DSS, accessing the DSS via the FSS screen. So, when nearing a planet, switch to FSS, and then call access the DSS functionality from there.